30 Sep 2022
30 Sep 2022
Status: this preprint is currently under review for the journal GChron.

DQPB: software for calculating disequilibrium U-Pb ages

Timothy John Pollard1,2, Jon David Woodhead1, John Charles Hellstrom1, John Engel1, Roger Powell1, and Russell Neil Drysdale1,2 Timothy John Pollard et al.
  • 1School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Melbourne, Victoria 3010, Australia
  • 2EDYTEM UMR CNRS 5204, Université Savoie Mont Blanc, F-73376 Le Bourget du Lac Cedex, France

Abstract. DQPB is software for calculating U-Pb ages while accounting for the effects of radioactive disequilibrium among intermediate nuclides of the U-series decay chains. The software is written in Python and distributed both as a pure Python package, and a stand-alone GUI application that integrates with standard Microsoft Excel spreadsheets. The software implements disequilibrium U-Pb equations to compute ages using various approaches, including concordia-intercept ages on a Tera-Wasserburg diagram, disequilibrium U-Pb isochron ages, Pb/U ages based on single analyses, and modified 207Pb ages. These age calculation approaches are tailored toward young materials that cannot reasonably be assumed to have attained radioactive equilibrium at the time of analysis, although they may also be applied to older materials where disequilibrium is no longer analytically resolvable. The software allows users to implement a variety of regression algorithms using both classical and robust statistics approaches, compute weighted average ages, and construct customisable, publication-ready plots of U-Pb age data. Age uncertainties are propagated using Monte Carlo methods.

Timothy John Pollard et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gchron-2022-24', Pieter Vermeesch, 31 Oct 2022
  • RC2: 'Comment on gchron-2022-24', Ryan Ickert, 10 Nov 2022

Timothy John Pollard et al.

Data sets

Sambe-Kisuki tephra LA-ICP-MS zircon example U-Pb data set Shuhei Sakata (unpublished)

CCB6 stalagmite example U-Pb data set Timothy Pollard, Jon Woodhear, John Hellstrom and Russell Drysdale (unpublished)

Timothy John Pollard et al.


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Short summary
When using the uranium-lead radiometric dating method on very young materials (e.g. Quaternary age zircon and carbonate minerals), it is important to accurately account for the production and decay of intermediate ‘daughter’ isotopes in the U-series decay chain. DQPB is open-source software that allows users to easily make such corrections for a variety of sample types and to produce publication-ready graphical outputs of the resulting age information.